Along with the recent development of information and telecommunication technology, various wireless communication techniques have been developed. Among them, the WLAN enables a user to wirelessly access the Internet based on radio frequency technology in a home, an office, or a specific service area using a portable terminal such as a Personal Digital Assistant (PDA), a laptop computer, a Portable Multimedia Player (PMP), a smartphone, etc.
To overcome limitations in communication speed that the WLAN faces, the recent technical standards have introduced a system that increases the speed, reliability, and coverage of a wireless network. For example, the Institute of Electrical and Electronics Engineers (IEEE) 802.11n standard has introduced Multiple Input Multiple Output (MIMO) that is implemented using multiple antennas at both a transmitter and a receiver in order to support High Throughput (HT) at a data processing rate of up to 540 Mbps, minimize transmission errors, and optimize data rates.
In recent times, to support increased numbers of devices supporting WLAN, such as smartphones, more Access Points (APs) have been deployed. Despite increase in use of WLAN devices supporting the Institute of Electrical and Electronics Engineers (IEEE) 802.11ac standard, that provide high performance relative to WLAN devices supporting the legacy IEEE 802.11g/n standard, a WLAN system supporting higher performance is required due to WLAN users' increased use of high volume content such as a ultra high definition video. Although a conventional WLAN system has aimed at increase of bandwidth and improvement of a peak transmission rate, actual users thereof could not feel drastic increase of such performance.
Developments in HEW aim at improving performance felt by users demanding high-capacity, high-rate services while supporting simultaneous access of numerous stations in an environment in which a plurality of APs is densely deployed and coverage areas of APs overlap. However, there is no specified method for a frame exchange including uplink single user transmission or uplink multiple user transmission in a HEW.